This invention relates to a process and apparatus for treating an edge of a plate glass, and more particularly to a process and apparatus for rounding off the corners of the edge of the plate glass.
It is well known in the art, that the corners of the edge of a plate glass are rounded off by being grinded with a grinding wheel carrying diamond abrasive or a circular grinding belt carrying abrasive. This grinding operation is, in general, carried out by rotating the grinding wheel or the grinding belt and by moving it along the edge of the plate glass.
However, such grinding operations encounter the following problems: the corners of the edge of the plate glass are considerably liable to chip off at an initial period of the grinding operation, and the surface rounded off is liable to have fine stripe markings along the length of the edge of the plate glass. Such defects are conspicuous particularly when using the grinding wheel, and those defects greatly contribute to lowering the values of the final products. Additionally, by the above-mentioned grinding operations, it is liable to occur that there remain fine streaks on the rounded edge surface of the plate glass, which streaks may lead to the breakdown of the plate glass.
Furthermore, in case of preparing window glasses, it has been necessary to further grinding the rounded edge of the plate glass with a fine grinding wheel after the above-mentioned step of rounding off the edge, in order to improve the smoothness and to polish the surface of the rounded edge. During this further grinding, it is necessary to apply a liquid such as water to cool and wash down the portion being ground. This is very troublesome and contributes to deterioration of the working environment.